n8n: MCP Browser HTTP Transport Exposes Unauthenticated Browser-Control Sessions
Impact
When @n8n/mcp-browser is run in HTTP transport mode, the MCP endpoint accepts session initialization and tool invocation requests without any authentication. Any network-reachable client, or any website visited by the user, can establish an MCP session and invoke browser-control tools.
Where the n8n AI Browser Bridge extension is installed and a browser connection is active, an unauthenticated caller can access browser-control capabilities including navigation, JavaScript evaluation, and cookie and storage access against the user's real browser profile.
This issue only affects instances where @n8n/mcp-browser is run with the HTTP transport (--transport http). The default transport is stdio, which is not affected.
Patches
The issue has been fixed in n8n versions 2.25.7, and 2.26.2. Users should upgrade to one of these versions or later to remediate the vulnerability.
Workarounds
If upgrading is not immediately possible, administrators should consider the following temporary mitigations:
- Avoid running
@n8n/mcp-browserwith the HTTP transport; use the default stdio transport instead. - If HTTP transport is required, restrict network access to the listening port to trusted clients only using host-based firewall rules.
These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | n8n | >= 2.26.0, < 2.26.2, < 2.25.7 | 2.26.2, 2.25.7 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L- Weakness (CWE)
CWE-306- Platform
- npm
- Package
n8n- Disclosed
- 16.06.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-qrx8-25qr-5r7v - CC BY 4.0
Vulnerability history: n8n
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 156
- First → latest
- 05.2023 09.2026
- Without a fix
- 1
- Exploited in attacks
- 1
Severity breakdown
- Critical 24
- High 58
- Medium 74
Disclosures per year
- 2023: 3
- 2024: 0
- 2025: 14
- 2026: 139
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n8n: MCP Browser HTTP Transport Exposes Unauthenticated Browser-Control Sessions this entry
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